/Ylsymbol
When you compile a module with /Yc and /Ylsymbol, the compiler creates a symbol similar to __@@_PchSym_@00@...@symbol, where the ellipsis (...) represents a linker-generated character string, and stores it in the object module. Any source file that you compile with this precompiled header refers to the specified symbol, which causes the linker to include the object module and its debugging information from the library.
This option is useful if you attempt to create a debugging library that uses precompiled headers and the build fails. You may generate LNK1211. When you specify the /Yc and /Z7 options, the compiler creates a precompiled header file that contains debugging information. An error can occur when you store the precompiled header in a library, use the library to build an object module, and the source code does not refer to any of the functions the precompiled header file defines.
To solve the problem, specify /Ylsymbol, where symbol is the name of an arbitrary symbol in the library, when you create a precompiled header file that does not contain any function definitions. This option directs the compiler to store the debugging information in the precompiled header file.
Compiler Options | Setting Compiler Options | Precompiled Header Compiler Options